Recent research on attention in adults has distinguished three separate components of attention: alertness, selectivity, and processing capacity. Studies have shown that these components may be isolated along a time dimension and that they operate independently on incoming visual information. Current studies of age trends in visual information processing have revealed striking differences in attention and memory between children and adults. The present proposal outlines a program of research to investigate more precise@y the exact nature of observed age differences in attention. Using tachistoscopic procedures with age groups from five years of age through adulthood, studies are designed to examine whether age differences in attention reflect differences in alertness, selectivity, or processing capacity. It is hoped that the research outlined here will provide a more fine-grained analysis of developmental trends in visual information-processing skills.